3 15kW motor needs 240mm2 cable. Consider the safe carrying capacity of the cable. The safe current carrying capacity of the cable is about 4 6A per square millimeter. The cable can bear the rated current of the motor with a certain margin, and the current carrying capacity of the cable is selected to be greater than or equal to the rated current of the motor. 3 15kW motor, 240mm2 cable is suitable. The current carrying capacity of 240mm2 cable can meet the requirements of 3 15kW motor and provide a certain safety margin.